His psychosis resurfaced in the weeks before the trial when he was left “paranoid and incoherent” and special hearings were held to decide whether he was going to be fit to take part.

In interviews with psychiatrists he admitted he had killed Lee Rigby, telling one: “My intention was to follow the Koran which says to fight pagans who live amongst you.”

As a teenager, Adebowale was involved in the Woolwich Boys, a notorious London street gang dominated by Muslim youths of Somali origin.

In 2008, his friend Faridon Alizada, 18, was murdered by Lee James who, suffering from a drug-induced psychotic episode, thought he, Adebowale and others were al-Qaeda terrorists.

In fact the gang was selling drugs from the flat where the murder happened and Adebowale was stabbed in the shoulder and hand.

Psychiatrists later identified the attack as the start of psychological problems for Adebowale, exacerbated by his heavy smoking of skunk cannabis.

But it also emerged that Adebowale had been an impressionable boy in 2001 and affected by the September 11 attacks on America’s World Trade Center.

Psychiatrist Dr Philip Joseph told the court how Adebowale told him that when he saw the 9/11 attacks on television he could not comprehend it and “I felt like I had been brainwashed by society from an early age”.

While he accepted al Qaeda had carried out the attack he believed there was still a Western conspiracy because the authorities could have stopped if wanted to but they did not.

In a separate, early hearing Dr Neil Boast, who examined Adebowale after his arrest for Fusilier Rigby’s murder, told the court he had most recently had “auditory hallucinations” for about 20 months, which was a sign of being “out of touch with reality”.

Among the voices he heard was that of Lee James and he became paranoid while being held in Belmarsh high security prison, that the killer was in there with him.

Another voice was in a Nigerian accent which told him what he was going to do next, even mundane actions such as brushing his teeth.

Dr Boast said: “What we have here is a man who had psychological symptoms in the years before.

“He is likely to have a serious enduring condition.”

Dr Ian Cumming, who treated him in Belmarsh, said there was a “clear history of psychosis from 2008, post traumatic anxiety” which had to be considered alongside cannabis misuse.

Adebowale talked about Jinns – spiritual creatures mentioned in the Koran – “playing with him or tormenting him or making him do things”.

“He read the bible and the Jinns knew it and were playing with him,” he said.

The trauma of the 2008 attack coincided with Adebowale’s conversion to Islam, which came two months later.

By 2009 he had taken to wearing Islamic robes and became more heavily involved in the more extreme versions of the religion, including handing out extremist literature.

Like Michael Adebolajo, Adebowale came from a Christian Nigerian family who desperately tried to keep him away from the dark route he was going down.

He was even mentored by Richard Taylor, the father of murdered schoolboy Damilola, but to little effect.

Adebowale, who was known as Toby to his friends, is the son of Juliet Obasuyi, a 43-year-old probation officer, and Adeniyi Adebowale, who works at the Nigerian High Commission in London.

The couple split up after Michael was born and Mrs Obasuyi was left to bring the youngster up.

In 2011, after her son had dropped out of university, she told a neighbour: "Michael is not listening any more. His older sister is a good Christian with a degree but Michael is rebelling as he has no father figure, dropping out of university and handing out leaflets in Woolwich town centre.”

Friend Steve Adebiyi said she was often left in tears after speaking to him on the phone.

"She said he was in with some bad group and causing a lot of trouble. They brainwashed him,” he said.

Mr Taylor mentored Adebowale when he was at school and last saw him in March – just two months before the murder – but he was already a fully committed Islamist militant by then.

Shortly after Mr Rigby’s murder, Mr Taylor said Adebowale and Adebolajo do not deserve to live.

Mrs Obasuyi, who is understood to be single now, raised Adebowale in Woolwich and Greenwich along with his half sister. Adebowale attended Kidbrooke School in Greenwich.

While at Kidbrooke, Adebowale was involved in a school play that foretold the events leading up to the Woolwich murder.

He played a character who became involved with a bad crowd and was arrested by police while carrying a gun in a short drama that he co – wrote for his GCSE coursework six years ago.

A classmate, who was in the same year as Adebowale, described him as "weird" and "easily influenced".

He told The Daily Telegraph: "I always got the feeling that there was something wrong with him. He used to do weird things, but I just used to think that was part of his personality.

"I used to laugh it off. I never knew I was laughing off something this big."

He heard little more about him until he saw a picture of one of the suspects in the Woolwich murder. "Straightaway I was like, 'Oh my God, that's Michael, that's crazy, that's scary'.”